extract_grob_set (me, "note-heads", heads);
if (to_boolean (me->get_property ("join-heads"))
&& heads.size () > 1)
{
Grob *common
extract_grob_set (me, "note-heads", heads);
if (to_boolean (me->get_property ("join-heads"))
&& heads.size () > 1)
{
Grob *common